Natures
Quiet raises Sp. Atk by 10% and lowers Speed by 10%. It is applied at the very end of the formula, after IVs and EVs, so the higher the stat, the more the nature gives and takes.
Special power for slow Pokémon — under Trick Room one of the better natures, outside it loses the turn to faster foes.
Flavor
Likes Dry, dislikes Sweet. This matters for Poffins, Pokéblocks and Berries: a Pokémon eats a disliked flavor reluctantly, and healing works worse.